Silacyclobutenes, methods for the preparation thereof, and polymers containing silacyclobutene units are known in the art. For example, Auner et al. disclose the synthesis of silacyclobutenes by reaction of equimolar amounts of trichlorovinylsilane and tert-butyllithium in the presence of acetylene derivatives (Angew. Chem. Int. Ed. 1991, 30, 9, 1151-1152). In this manner, the following silacyclobutenes were obtained in 50-80% yield: 1,1-dichloro-2,3-dimethyl-4-neopentyl-1-silacyclobut-2-ene; 1,1-dichloro-4-neoptenyl-2,3-bis(trimethylsilyl)-1-silacyclobut-2-ene; 1,1-dichloro-4-neopentyl-2,3-diphenyl-1-silacyclobut-2-ene; 1,1-dichloro-3-methyl-4-neopentyl-2-(trimethylsilyl)-1-silacyclobut-2-ene; 1,1-dichloro-4-neopentyl-3 -phenyl-2-(trimethylsilyl)-1-silacyclobut-2-2-ene; and 1,1-dichloro-3-methyl-4-neopentyl-2-phenyl-1-silacyclobut-2-ene. The silacyclobutenes are reportedly thermally stable and do not decompose even on heating for several days at 200.degree. C.
Auner et al. disclose the synthesis of silacyclobutenes by reacting chlorovinylsilanes, tert-butyllithium, and diorganoacetylenes (Organometallics 1993, 12, 10,4135-4140). In addition to the silacyclobutenes reported in the previous reference, the following compounds were obtained: 1,1-dichloro-2,3-dimethyl-4-neopentyl-4-phenyl-1-silacyclobut-2-ene; 1,1 -dichloro-4-neopentyl-4-phenyl-2,3-bis(trimethylsilyl)-1 silacyclobut-2-ene 1,1-dichloro-4-neopentyl-2,3 ,4-triphenyl-1-silacyclobut-2-ene; 1,1-dichloro-3-methyl-4-neopentyl-4-phenyl-2-(trimethylsilyl)-1-silacyclob ut-2-ene; 1,1-dichloro-4-neopentyl-3,4-diphenyl-2-(trimethylsilyl)-1-silacyclobut-2- ene; 1,1-dichloro-3-methyl-4-neopentyl-2,4-diphenyl-1-silacyclobut-2-ene; 2,3-dimethyl-4-neopentyl-1,1-bis(trimethylsiloxy)-1-silacyclobut-2-ene; 4-neoptenyl-1,1-bis(trimethylsiloxy)-2,3 bis(trimethylsilyl)1-silacyclobut-2-ene; 4-neopentyl-2,3 -diphenyl-1,1-bis(trimethylsiloxy)-1-silacyclobut-2-ene; 3 -methyl-4-neopentyl-1,1-bis(trimethylsiloxy)-2-(trimethylsilyl)-1-silacycl obut-2-ene; 4-neopentyl-3 -phenyl-1,1-bis(trimethylsiloxy)-2(trimethylsilyl)-1-silacyclobut-2-ene; and 3 -methyl-4-neopentyl-2-phenyl-1,1-bis(trimethylsiloxy)-1-silacyclobut-2-ene . The authors report that the silacyclobutenes have surprising thermal stability and can be distilled in most cases under vacuum at temperatures up to 200.degree. C. without decomposition.
U.S. Pat. No. 5,777,051 to Auner et al. discloses monosilacyclobutene monomers, spiro-type cyclosiloxy-silacyclobutene monomers, and silane polymers containing such silacyclobutene units. One type of monosilacyclobutene monomer has the formula: ##STR2## wherein R.sup.1 and R.sup.2 are halogen or alkoxy, R.sup.3 and R.sup.4 are hydrogen or alkyl having 2 to 10 carbon atoms, and R.sup.5 and R.sup.6 are aryl. Another type of monosilacyclobutene monomer has the formula: ##STR3## wherein R.sup.29 and R.sup.30 are hydrogen or alkyl having 2 to 10 carbon atoms; R.sup.31 and R.sup.33 are hydroxyl, alkyl, aryl, alkenyl, or alkynyl; and R.sup.32 and R.sup.34 are aryl. The silacyclobutene monomers and silacyclobutene polymers reportedly exhibit strong photoluminescence in the blue region of the visible spectrum when excited by ultraviolet light with a wavelength of 337 nm.
UK Patent Application GB 2326417 to Auner et al. discloses silacyclobutane compounds, silacyclobutene compounds, and siloxane polymers containing silacyclobutane and/or silacyclobutene units. The silacyclobutene compounds have the formula: ##STR4## wherein R.sup.1, R.sup.4, and R.sup.5 are independently a hydrocarbon group or hydrogen; R.sup.6 is alkyl having at least 4 carbon atoms; X is a hydrolyzable group; and R.sup.8 is R.sup.1 or X. Examples of X include halogen and hydrocarbonoxy. The UK patent application teaches that R.sup.1 and R.sup.4 are preferably aromatic hydrocarbon groups. The silacyclobutene compounds are reportedly prepared by cycloaddition of a silene and an acetylene. The UK patent application also teaches that the siloxane polymers have improved resistance to low temperatures.
Although the above-cited references disclose various silacyclobutene compounds, none of the references teach the silacyclobutene compounds of the present invention having a vinylic group attached to the ring C-3 position, the methods of preparing the silacyclobutene compounds, the silane polymers, or the siloxane polymers of the present invention.